Process for separating para-cresol from a mixture of methylated and ethylated phenols

ABSTRACT

Para-cresol is separated from a mixture comprising meta-cresol and various other methylated and ethylated phenols by preferentially complexing the para-cresol with one or more anhydrous or dehydrated inorganic salts selected from the group consisting of calcium bromide, lithium bromide, manganese bromide and magnesium chloride. The anhydrous inorganic salt is added to the phenolic mixture in an amount to give a mole ratio of salt to para-cresol in the mixture in the range of about 0.5 mole to one to about 1.5 mole to one. The para-cresol and salt form a complex and the complex is removed from the mixture of methylated and ethylated phenols. Then the complex is decomposed to recover the para-cresol and salt; the recovered salt may be recycled to complex with more para-cresol.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is related to applications entitled "Process forObtaining Para-Cresol and Meta-Cresol from a Mixture of Methylated andEthylated Phenols Containing Meta- and Para-Cresol," Ser. No. 53,532"Process for Obtaining Para-Cresol and Meta-Cresol from a Mixture ofMethylated and Ethylated Phenols Characterized by Urea Clathration ofMeta-Cresol," Ser. No. 53,531 and "Process for Obtaining Para-Cresol andMeta-Cresol from a Mixture of Methylated and Ethylated PhenolsCharacterized by Selective Complexation with Calcium Bromide and SodiumAcetate," Ser. No. 53,195 all of Gerd Leston, filed on June 29, 1979,which applications are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

The present invention is directed to a process for separatingpara-cresol from a mixture of methylated and ethylated phenols. Moreparticularly, the process of the present invention is directed toseparating para-cresol from a phenolic mixture containing meta-cresol.

Mixtures of phenolic compounds are derived from coal as products of coalcarbonization, or as the middle oil from the hydrogenation of coal, orfrom petroleum as alkali extracts of cracked petroleum distillate. Someof the phenolic compounds in the mixtures derived from these sourceshave similar physical properties. These similarities in properties makeit difficult to separate some of the phenolic compounds from each other.Para-cresol is, in particular, difficult to separate from other phenoliccompounds having similar properties. For example, para-cresol isdifficult to separate from meta-cresol, since both compounds havesimilar boiling points, namely, 201.8° C. and 202.8° C., respectively.The similarity of boiling points of these two compounds precludes theirseparation practically by fractional distillation.

There are several known methods for separating para-cresol andmeta-cresol isomers from a mixture containing the isomers, such as acommercial mixture having 40-65 percent of meta-cresol. These methodsinclude treatment of a mixture containing meta- and para-cresol isomerswith complexing agents such as urea, sodium acetate, oxalic acid or thelike and separation of the meta- or para-cresol isomers in an adductform. Other methods include the formation of a solid complex between areagent and one cresol isomer. The reagents used includeortho-toluidine, oxalic acid and hexamethylenetetramine. Still othermethods for separating meta- and para-cresol isomers involve azeotropicdistillation with benzyl alcohol, or selective solvent extraction withmethanol-ligroin, or hydrolysis of the sulfonic acid of meta- orpara-cresol, or dibutylation followed by distillation. Another recentlysuggested method for separating meta-cresol and para-cresol isomerstakes advantage of the different melting points of the compounds andinvolves subjecting the meta- and para-cresol isomer mixture tocrystallization at pressures of not less than about 300 atmospheres.Only a few of the foregoing methods of separation have any commercialpotentialities, the process usually employed being the butylationmethod. A more efficient method is thus desired to obtain high puritypara-cresol and high purity meta-cresol from mixtures of methylated andethylated phenols containing compounds such as ortho-ethyl phenol,xylenol and other methylated and ethylated phenols having similarboiling points to para-cresol and meta-cresol.

An article entitled "Rapid Separation of Organic Mixtures by Formationof Metal Complexes," Journal Organic Chemistry, Volume 40, No. 9, 1975,Sharpless, Chong and Scott, describes a convenient and efficienttechnique for resolving alcohol mixtures. The technique involvespreferential complexing of an alcohol by calcium chloride or manganesechloride, examples of useful alcohols beng cis- andtrans-4-tert-butylcyclohexanol, geraniol, and cyclohexanol. The articlefurther notes that other alcohols, such as large and hindered alcohols,form complexes very slowly, and that the speed of complex formation canbe increased by using a small amount of a lower aliphatic alcohol as acatalyst for complexing.

SUMMARY OF THE INVENTION

It has been found that para-cresol complexes with certain anhydrous ordehydrated inorganic salts, such as calcium bromide, lithium bromide,manganese bromide and magnesium chloride, preferentially over othermethylated and ethylated phenolic compounds. This preferentialcomplexing can be used as a means for separating and purifyingpara-cresol from a mixture of methylated and ethylated phenols that havesimilar boiling points to para-cresol.

The process of the present invention comprises adding to a mixture ofmethylated and ethylated phenols containing para-cresol and usuallymeta-cresol one or more anhyrous inorganic salts selected from the groupconsisting of calcium bromide, lithium bromide, manganese bromide andmagnesium chloride in a mole ratio of anhydrous or dehydrated inorganicsalt to para-cresol in the mixture in the range from about 0.5 to one toabout 1.5 to one, in the presence of a non-aqueous solvent to produce acomplex between the inorganic salt and the para-cresol, whereby thecomplex formed may be separated from the mixture and then decomposed toyield para-cresol.

Another feature of the present invention is the production of thesalt-para-cresol complex in the presence of meta-cresol. This complexcan be used to initiate complexing with those anhydrous inorganic saltsthat are slower in forming complexes with the para-cresol. Also, thecomplex can be used as a chemical intermediate in producing purifiedpara-cresol.

In the process of the present invention an important variable is thesalt to para-cresol mole ratio, and to a lesser extent the variables ofpara-cresol concentration in the mixture of methylated and ethylatedphenols, the solvent used and the temperature of complexing. Thesalt/para-cresol mole ratio is generally in the range of about 0.5 toone to about 1.5 to one. The para-cresol concentration can be anyconcentration but generally is at least that concentration that can bepurified or separated economically. The solvent must be a non-aqueoussolvent, since water will react with the anhydrous inorganic salt toform one or more hydrates. Generally, the non-aqueous solvent shouldnot, itself, complex with the salt or at least not more readily than thepara-cresol. The addition of the salt to the mixture of methylated andethylated phenols can be initially with or without the use of a solvent,but once the salt is added a solvent should then be employed tofacilitate the mixing of the salt and mixture. Generally, thetemperature of complexing ranges from ambient temperature to atemperature of around 130° C. Higher temperatures are favored when theamount of para-cresol in the mixture is small, that is, around 10percent by weight. If the complex formation is not initiated at thehigher temperatures, then the temperature can be lowered to initiatecomplex formation and then raised to the higher temperature. If thecomplex formation is slow, an initiator such as a lower aliphaticalcohol or a previously formed complex of salt and para-cresol can beused.

Once the complex is formed it can be separated from the mixture by anymethod known to those skilled in the art for separating solid complexesfrom liquids. Once separated, the complex can be decomposed by thermaldecomposition at atmospheric pressure, or by distillation at reducedpressure, or by treatment with water, or by treatment with alcohol.After the complex is decomposed, the purified para-cresol is recoveredin a second mixture and the anhyrous inorganic salt can be recycled forfurther complex formation with para-cresol. It is a feature of theinvention that the recovered inorganic salt may be recycled andintroduced back into the second mixture containing the previouslypurified para-cresol and minor amounts of meta-cresol and othermethylated and ethylated phenols. The second mixture will thus contain arecomplexation product of para-cresol and salt, which product is thenseparated and thereafter decomposed to recover the para-cresol and salt.The successively purified para-cresol will then be contained in a thirdmixture, also containing successively lower amounts of meta-cresol andother phenolic compounds. The para-cresol may thus be treatedsequentially with the inorganic salt to provide successive mixtureshaving higher and higher concentrations of para-cresol and lower amountsof other phenolic compounds.

DETAILED DESCRIPTION OF THE INVENTION

In the process of the present invention para-cresol can be separated orpurified from a mixture of methylated and ethylated phenols havingsimilar boiling points to the para-cresol and meta-cresol. Themethylated and ethylated phenolic compounds are those methylated andethylated phenols that do not form complexes with the anhydrousinorganic salts of calcium bromide, lithium bromide, manganese bromideand magnesium chloride or that are not thermodynamically favored overthe para-cresol complex or that form complexes at a slower rate thanpara-cresol. Examples of these methylated and ethylated phenoliccompounds include meta-cresol, ortho-cresol, ortho-ethylphenol,2,4-xylenol, 2,5-xylenol, 2,6-xylenol and trimethylphenols. It ispreferred that the mixture contain only para-cresol and meta-cresol, forexample, the commercial mixture of meta- and para-cresol containing from40 to 65 percent of the meta-cresol, the remainder being para-cresol.

It has been found that certain anhydrous or dehydrated inorganic saltswhen used in a certain mole ratio to the para-cresol in the mixture ofmethylated and ethylated phenols preferentially complex with thepara-cresol. It is believed, but the invention is not limited by thisbelief, that the para-cresol-salt complex is thermodynamically favoredover other complexes formed by methylated and ethylated phenols in themixture. This belief is based on the fact that even though otheralkylated phenols, e.g., meta-cresol, in the mixture form complexes withthe above-mentioned anhydrous inorganic salts, the para-cresol complexis the predominant complex formed. A few of the methylated and ethylatedphenolic compounds in the mixture, most notably ortho-cresol, do notreadily form complexes with the anhydrous or dehydrated inorganic salts.Also, the complexing of para-cresol appears to be thermodynamicallycontrolled whereas the complexing of meta-cresol is kineticallycontrolled. Although the meta-cresol-salt complex will form first, thepara-cresol-salt complex is more thermodynamically stable than themeta-cresol-salt complex. Therefore, given a necessary period of timeformation of the para-cresol-salt complex will predominate over themeta-cresol-salt complex.

The amount of para-cresol in the mixture of methylated and ethylatedphenols and preferably the mixture of para- and meta-cresol can bepractically any amount of para-cresol above about 10 weight percent,since any amount of para-cresol can be separated from the mixture aslong as the proper mole ratio of salt to para-cresol is used. Theprocess of the present invention can be used to enrich a mixturecontaining para-cresol and this enrichment can be done fractionally soas to obtain the maximum enrichment of the mixture in para-cresol.Hereinafter and in the claims of this specification the term"separation" is intended to cover separation, purification andenrichment of para-cresol in mixtures of methylated and/or ethylatedphenolic compounds. Generally, it is preferred that the para-cresol bepresent in the mixture in an amount of at least about 25 weight percent.

In the process of the present invention one or more anhydrous inorganicsalts (hereinafter referred to as salt) selected from the groupconsisting of calcium bromide, lithium bromide, manganese bromide ormagnesium chloride is added to the mixture containing para-cresol. Theaddition is in an amount to give a mole ratio of the salt to thepara-cresol in the mixture in the general range of about 0.5 to one toabout 1.5 to one. If the mole ratio of salt to para-cresol is aboveabout 1.5 to one, other methylated or ethylated phenolic compounds maycomplex or may complex to a greater extent and complicate the separationof the para-cresol from the mixture. If the mole ratio of salt topara-cresol is below about 0.5 to one, then the maximum amount ofpara-cresol present in the mixture will not be separated and the yieldof the process would be decreased. The preferred mole ratio of salt topara-cresol depends on the particular salt used. For calcium bromide thepreferred mole ratio of salt to para-cresol is about 0.8 to one to about1.2 to one. The preferred mole ratio of salt to para-cresol for lithiumbromide is in the range of about 0.8 to one to about 1.2 to one. Formanganese bromide the preferred mole ratio of salt to para-cresol is inthe range of about 0.8 to one to about 1.2 to one. The preferred moleratio of salt to para-cresol for magnesium chloride is in the range ofabout 0.8 to one to about 1.2 to one. To obtain the mole ratio of saltto para-cresol in the mixture, it is necessary to determine the amountof para-cresol in the mixture of methylated and/or ethylated phenoliccompounds. This can be done by any analytical technique known to thoseskilled in the art for determining the amount of para-cresol in mixturesof organic compounds.

The anhydrous inorganic salts of calcium bromide, lithium bromide,manganese bromide or magnesium chloride that are used in the process andcomposition of the present invention are the commercial anhydrous saltsor the hydrated forms of the salts that have been dehydrated.Dehydration of the salts can be in any manner known to those skilled inthe art. Anhydrous salts may be readily prepared from hydrated formssuch as aqueous solutions or flaked hydrate forms. It is preferred toheat either the aqueous or flaked form to around 200° C. in air to givethe anhydrous material in a solid chunk, which may then be ball milledor ground for use.

The addition of the proper amount of salt can be performed in thepresence or absence of a non-aqueous solvent. If the solvent is notpresent upon the initial addition, it must be added at a later time whenupon formation of the complex the mixing of the salt and the mixturebecomes difficult. The non-aqueous solvent is added to an amount tofacilitate mixing of the components. The non-aqueous solvent should notcomplex with the salt, or at least it must complex to a lesser extentthan the para-cresol. A few examples of non-aqueous solvents that can beused are benzene, toluene, methylene chloride, chlorobenzene,o-dichlorobenzene, and lower aliphatic alicyclic compounds such ashexane as well as oxygenated compounds like ethers, ketones and esters,provided that any complex that is formed with the solvent is weaker thanthe complex formed with para-cresol. The preferred non-aqueous solventis toluene because of its low cost.

During the addition of the components and during complexing of the saltand para-cresol-containing mixture, the temperature is in the range ofabout 20° C. to about 50° C. at atmospheric pressure. Ifsuperatmospheric or subatmospheric pressures are employed, thetemperature will change accordingly. Increasing the temperaturemoderately within the range during complexing will increase the rate ofcomplex formation. If the complex is not initiated at the highertemperatures within the above range, the temperature can be lowered toinitiate complexing and then raised to increase the rate of complexing.The higher temperatures are preferred when there is a small amount,e.g., around 15 weight percent, of para-cresol in the mixture.

If complex formation with a particular salt is not initiated within areasonable time, an initiator may be used to catalyze complex formation.Examples of useful initiators include n-aliphatic alcohols such asanhydrous ethanol, anhydrous propanol and anhydrous butanol. Acatalytically effective amount of initiator to be used would be around 1to about 10 weight percent. Alternatively, a useful initiator is apreviously formed complex of para-cresol with calcium bromide, lithiumbromide, manganese bromide or magnesium chloride. A catalyticallyeffective amount of the complex used may be in the range of about 1 toabout 10 weight percent of the mixture being treated. It is preferred touse anhydrous ethanol as a complex initiator or, alternatively, thecomplex of the same salt used in the complex.

The time taken for complex formation varies for the particular saltused. Lithium bromide is extremely fast in forming the complex with thepara-cresol while calcium bromide, magnesium chloride and manganesebromide are somewhat slower. Lithium bromide forms the complex withinaround 3 to 5 minutes compared with several hours for the other salts.The preferred anhydrous inorganic salt is calcium bromide since it hashigh selectivity and gives good conversions.

The complex formation of para-cresol and the anhydrous inorganic saltcan be performed in any conventional reaction equipment, since themixture and salt are not very corrosive. Also, complexing can beperformed in a batch manner or continuous manner.

Once the para-cresol-salt complex, preferably the para-cresol calciumbromide complex, is formed, the complex is separated from the mixture ofmethylated and ethylated phenols. This separation can be by any methodand in any equipment known to those skilled in the art for separating asolid complex from a liquid solution. Preferably, the complex isseparated by filtration or centrifugation to produce a supernatantliquid of methylated and ethylated phenols and a para-cresol-saltcomplex. The para-cresol-salt complex contains predominantly para-cresolcomplexed with the salt but may also contain small amounts ofmeta-cresol and other methylated and ethylated phenols complexed withthe salt.

The filtered complex of para-cresol and the salt may be washed withsolvent and is then decomposed to release the para-cresol and recoverthe salt that can be recycled for additional complexing. Thedecomposition can be performed by heating the complex to thedecomposition temperature of about 200° C. at atmospheric pressure or bydistilling the complex at a reduced pressure, or by hydrolysis, or bycleavage with other agents like alcohol. Thermal decomposition is thepreferred manner for releasing the para-cresol and recovering the saltsince it is the most economic method of decomposition. Thermaldecomposition can be performed in any equipment known to those skilledin the art to be useful in conducting decomposition reactions.Preferably, the thermal decomposition is performed in a Rinco evaporatorat temperatures up to about 200° C. and at atmospheric pressure.Alternately, the complex can be decomposed at a temperature of 125° C.to 175° C. under reduced pressures. An advantage of thermaldecomposition over hydrolysis is that an activated form of the salt isthus prepared which can be recycled to complex with para-cresol.Alternatively, the complex can be hydrolyzed with a sufficient amount ofwater to decompose all of the complex. Also, since alcohols formstronger complexes than phenolic compounds, the alcohols can be used tocleave the complex, the alcohol being substituted in the complex for thepara-cresol. A disadvantage of this decomposition method is that thesalt is not easily recoverable for recycling.

The recovered para-cresol contained in a second or purified mixture fromthe decomposition reaction is much purer than the original or firstmixture of methylated and ethylated phenolic compounds. The secondmixture containing para-cresol may also contain a minor amount ofmeta-cresol or ortho-ethyl-phenol. If ultimate purity is desired,successive mixtures of para-cresol can be complexed sequentially similarto fractional distillation. The anhydrous inorganic salt recovered afterdecomposition of the para-cresol-salt complex may be recycled to beadded to additional amounts of the mixture of methylated and ethylatedphenolic compounds containing para-cresol for additional complexing.

When a mixture of phenolic compounds contains only para-cresol andmeta-cresol, the process of the present invention yields a purifiedpara-cresol product and a purified meta-cresol product. The purifiedmeta-cresol product is obtained since it is left behind in the mixtureafter the para-cresol is complexed and removed. If the mixture ofmethylated and ethylated phenols contains other methylated and ethylatedphenols besides para-cresol and meta-cresol, any method known to thoseskilled in the art can be used to separate meta-cresol or othermethylated or ethylated phenols after para-cresol has been complexedwith the anhydrous inorganic salt.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a flow diagram of the preferred embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE DRAWING

The mixture of methylated and ethylated phenols from which para-cresolis separated may contain meta-cresol and minor amounts of other phenoliccompounds. This mixture enters a complexing zone 12 through conduit 10.The preferred anhydrous inorganic salt calcium bromide enters complexingzone 12 through conduit 14. The amount of calcium bromide added tocomplexing zone 12 is preferably an amount which will give a mole ratioof calcium bromide to para-cresol in the range of about 0.7 to one toabout 1.0 to one. A non-aqueous solvent, preferably toluene, is added tocomplexing zone 12 through conduit 16. In complexing zone 12,meta-cresol, para-cresol, toluene and calcium bromide are mixed at atemperature of around 100° C. for about eight hours. During this timetoluene is present in an amount sufficient for complete mixing of thecomponents during the complexing reaction. At the end of the mixingperiod, a substantial portion of para-cresol forms a complex withcalcium bromide. The complex, along with the supernatant liquidcontaining meta-cresol, and small quantities of ortho-cresol, xylenol,and ortho-ethylphenol, are removed by conduit 18 from complexing zone12.

The complex and supernatant liquid are conveyed through conduit 18 to afiltration zone 20, where the complex is separated from the supernatantmixture. The wet complex is conveyed from filtration zone 20 throughconduit 22 to a drying zone 24, where the complex is dried and thetoluene is separated from the complex. The toluene is then recycledthrough conduit 26 to conduit 28 where it is added with additionaltoluene and conveyed to filtration zone 20 to wash the wet complex. Thesupernatant liquid from which the para-cresol-calcium bromide complexhas been removed may be conveyed from filtration zone 20 through conduit30 and eliminated or may be circulated through conduit 32 back tocomplexing zone 12 for removal of residual para-cresol.

After the para-cresol-calcium bromide complex has been dried in zone 24,it is conveyed through conduit 34 to decomposition zone 36. In zone 36the complex is heated to a temperature of around 200° C. at atmosphericpressure to decompose the complex to produce para-cresol and toregenerate the calcium bromide salt. The para-cresol product leavesdecomposition zone 36 through conduit 38 and is of a purity of about 98percent. The regenerated calcium bromide leaves decomposition zone 36through conduit 14 and is conveyed to complexing zone 12. In analternative embodiment, additional calcium bromide can be added toconduit 14 through conduit 40 from an outside source.

The following examples set forth specific embodiments of the invention.However, the invention is not to be construed as being limited to theseembodiments for there are, of course, numerous possible variations andmodifications. All parts and percentages recited in the examples andthroughout the specification are by weight, unless otherwise specified.

EXAMPLE I

A reaction vessel equipped with heating means, stirring means and dryingmeans for removing water from the atmosphere in the reaction vessel, ischarged with 600 parts calcium bromide, 108 parts meta-cresol, 108 partspara-cresol, 3300 parts hexane and about 3 parts absolute ethanol (saltto meta-cresol to para-cresol molar ratio being 3 to 1 to 1). Themixture is heated with stirring to a temperature of 25° to 30° C. forabout nine hours. After the supernatant hexane solution is withdrawnfrom the reaction vessel, the solid reaction product is washed withsuccessive amounts of hexane until the wash solution is essentially freeof cresols. Water in excess is added to the reaction vessel forhydrolysis of the solid reaction product. Analysis is made on thehydrolyzate and on the supernatant solution at one week, one month andfour month intervals. Results are listed in Table I.

EXAMPLE II

A reaction vessel is equipped and charged with components as set forthin Example I, with the exception that the reaction mixture contains a 33percent increase in the amount of hexane. Reaction procedures aregenerally as outlined in Example I. Data from analysis of thehydrolyzate and supernatant solution are listed in Table I.

EXAMPLE III

A reaction vessel is equipped and charged with components as set forthin Example I, the molar ratio of the salt, meta-cresol and para-cresolcomponents being 1.5 to 1 to 1. The mixture is heated with stirring to atemperature of 25° to 30° C. for about eight hours. Reaction proceduresare generally as outlined in Example I. Data from analysis of thehydrolyzate and supernatant solution are listed in Table I.

EXAMPLE IV

A reaction vessel is equipped and charged with components as set forthin Example I, the molar ratio of calcium bromide, meta-cresol andpara-cresol being 1 to 1 to 1. Reaction procedures are generally as inExample I. Data from analysis of the hydrolyzate and supernatant liquidare listed in Table I.

EXAMPLE V

A reaction vessel is equipped and charged with components as set forthin Example I, the molar ratio of calcium bromide, meta-cresol andpara-cresol being 0.7 to 1 to 1. The mixture is heated with stirring toa temperature of 25°-30° C. for about 11 hours, reaction proceduresotherwise being generally as set forth in Example I. Data from analysisof the hydrolyzate and supernatant liquid are listed in Table I.

EXAMPLE VI

A reaction vessel is equipped and charged with components as set forthin Example V. The mixture is heated with stirring to a temperature of25°-30° C. for about nine hours, reaction procedures otherwise beinggenerally as set forth in Example I. Data from analysis of thehydrolyzate and supernatant liquid are listed in Table I.

EXAMPLE VII

A reaction vessel is equipped and charged with components as set forthin Example V, with a ten-fold scale-up in component amounts. The mixtureis heated with stirring to a temperature of 25°-30° C. for about ninehours. After the supernatant hexane solution is withdrawn from thereaction vessel, the solid reaction product is washed with successiveamounts of hexane until the wash solution is essentially free ofcresols. Ethanol in 50 percent molar excess to the solid complex ofcresol and salt is added to the reaction vessel holding the solidreaction product. Sufficient hexane is added to the reaction vessel fordissolving the cresol isomers displaced by the ethanol from the solidcomplex. The solid complex is washed successively with hexane andthereafter the combined hexane solutions, together with the salt-ethanolcomplex, are refluxed. The hexane and ethanol form an azeotrope which isdistilled from the solid salt, the distillate carrying with it thepara-cresol isomer. The solid salt, which is dried under reducedpressure, comprises calcium bromide. Data from analysis of thehydrolyzate and supernatant liquid are listed in Table I.

                  TABLE I                                                         ______________________________________                                        Calcium Bromide Complexes                                                                    Product                                                                                     Supernatant                                      Feed (Mole Ratio)                                                                              Hydrolyzate Solution                                                CaBr.sub.2 /m-cresol/                                                                       % m-    % p-  % m-  % p-                                 Example                                                                              p-cresol      cresol  cresol                                                                              cresol                                                                              cresol                               ______________________________________                                        I      3/1/1         41.7.sup.a                                                                            58.3.sup.a                                                                          95.5.sup.a                                                                          4.5.sup.a                                                 43.9.sup.b                                                                            56.1.sup.b                                                                          100.sup.b                                                       43.sup.c                                                                              57.sup.c                                                                            94.6.sup.c                                                                          5.4.sup.c                            II     3/1/1         48.sup.c                                                                              52.sup.c                                                                            93.5.sup.c                                                                          6.5.sup.c                            III    1.5/1/1       38.9    61.1  91.6  8.4                                  IV     1/1/1         7       93    88    12                                   V      0.7/1/1               100   71    29                                   VI     0.7/1/1               100   66    34                                   VII    0.7/1/1               100   65    35                                   ______________________________________                                         .sup.a Analysis made on oneweek-old sample.                                   .sup.b Analysis made on onemonth-old sample.                                  .sup.c Analysis made on fourmonth-old sample.                            

EXAMPLE VIII

A reaction vessel equipped as in Example I is charged with magnesiumchloride, meta-cresol and para-cresol in the molar ratio of 1.5 to 1 to1, with hexane and ethanol being added in the proportions as set forthin Example I. The mixture is heated to 25°-30° C. with stirring forabout 10 hours, other reaction procedures being generally as set forthin Example I. Data from analysis of the hydrolyzate and supernatantsolution are set forth in Table II.

EXAMPLE IX

A reaction vessel is equipped and charged with components as in ExampleVIII, with the exception that the magnesium salt, meta-cresol andpara-cresol are in molar ratio of 1 to 1 to 1. Reaction procedures aregenerally as set forth in Example VIII. Data from analysis of thehydrolyzate and the supernatant liquid are set forth in Table II.

EXAMPLE X

A reaction vessel is equipped and charged with components as in ExampleVIII. The mixture is heated to 25°-30° C. with stirring for about ninehours, other reaction procedures being generally as set forth in ExampleVIII. Data from analysis of the hydrolyzate and supernatant solution areset forth in Table II.

EXAMPLE XI

A reaction vessel is equipped and charged with components as set forthin Example VIII, the magnesium chloride, meta-cresol and para-cresolbeing in a molar ratio of 0.75 to 1 to 1. The mixture is heated to25°-30° C. with stirring for about nine hours, other reaction proceduresbeing generally as set forth in Example VIII. Data from analysis of thehydrolyzate and supernatant solution are set forth in Table II.

EXAMPLE XII

A reaction vessel is equipped and charged with components as set forthin Example VIII, the magnesium chloride, meta-cresol and para-cresolbeing in a molar ratio of 0.5 to 1 to 1. The mixture is heated to25°-30° C. with stirring for about 11 hours, other reaction proceduresbeing generally as set forth in Example VIII. Data from analysis of thehydrolyzate and supernatant solution are set forth in Table II.

EXAMPLE XIII

A reaction vessel is equipped and charged with components as set forthin Example XII. The mixture is heated to about 50° C. with stirring forabout 13 hours. After the supernatant hexane solution is withdrawn fromthe reaction vessel, the solid reaction product is washed withsuccessive amounts of hexane until the wash solution is essentially freeof cresols. The solid complex is heated to 200° C. at atmosphericpressure for four hours, then at about 0.2 atmosphere for two hours, atabout 0.13 atmosphere for one hour and at about 0.07 atmosphere for onehour. A portion of the dried solid complex is added as a "seed" crystalto a mixture of magnesium chloride, meta-cresol and para-cresol in amolar ratio of 0.5 to 1 to 1 in hexane. After eight hours there isobserved a 14 percent decrease in cresol concentration in thesupernatant liquid. The supernatant hexane solution is withdrawn fromthe reaction vessel and the solid complex is washed with successiveamounts of hexane. Water in excess is added to the solid products forhydrolysis of the complex. Data from analysis of the hydrolyzate and thesupernatant solution are set forth in Table II.

                  TABLE II                                                        ______________________________________                                        Magnesium Chloride complexes                                                                 Product                                                                                     Supernatant                                      Feed (Mole Ratio)                                                                              Hydrolyzate Solution                                                MgCl.sub.2 /m-cresol                                                                        % m-    % p-  % m-  % p-                                 Example                                                                              p-cresol      cresol  cresol                                                                              cresol                                                                              cresol                               ______________________________________                                        VIII   1.5/1/1       31.5    68.5  67.7  32.3                                 IX     1/1/1         8.3     91.7  75.1  24.8                                 X      1.5/1/1       46.2    53.8  64.5  35.5                                 XI     0.75/1/1      11.5    88.5  66.6  33.4                                 XII    0.5/1/1       11.5    88.5  66.6  33.4                                 XIII   0.75/1/1      27      73    62.3  37.7                                 ______________________________________                                    

Although specific examples of the instant invention have been set forthhereinabove, it is not intended that the invention be limited solelythereto, but is to include all the variations and modifications fallingwithin the scope of the appended claims.

What is claimed is:
 1. A process for obtaining predominantly para-cresolfrom a mixture of para-cresol and meta-cresol isomers, comprising thestep of:adding to the mixture one or more anhydrous or dehydratedinorganic halide salts selected from the group consisting of calciumbromide, lithium bromide, manganese bromide and magnesium chloride, inan amount to give a mole ratio of the inorganic salt to the para-cresolisomer in the mixture from about 0.5 to one to about 1.5 to one, in thepresence of a non-aqueous solvent to produce a complex predominantlywith the para-cresol isomer, the mixture having a temperature in a rangefrom about 20° C. to about 130° C. during the inorganic salt addingstep;whereby said complex may be separated from the mixture, and thendecomposed to yield predominantly the para-cresol and the anhyrousinorganic salt.
 2. The process of claim 1 wherein the mixture furtherincludes one or more phenolic compounds selected from the groupconsisting of ortho-ethylphenol, 2,4-xylenol, 2,5-xylenol, 2,6-xylenol,ortho-cresol and trimethyl phenols.
 3. The process of claim 1 wherein anon-aqueous solvent is added to the mixture simultaneously with saidanhyrous or dehydrated inorganic salt.
 4. The process of claim 1 whereinan initiator is used to promote complex formation of the para-cresolisomer with said anhyrous inorganic salt.
 5. The process of claim 4wherein said initiator is a lower aliphatic alcohol selected from thegroup consisting of ethanol, propanol or butanol.
 6. The process ofclaim 4 wherein said initiator is a complex of the para-cresol isomerand said anhydrous or dehydrated inorganic salt.
 7. The process of claim1 further comprising the steps of:separating said complex from themixture; and decomposing said complex to yield predominantly thepara-cresol isomer and said anhydrous inorganic salt.
 8. The process ofclaim 7 wherein said complex is separated from the mixture byfiltration.
 9. The process of claim 7 wherein said complex is decomposedby thermal decomposition at a temperature around 200° C. at atmosphericpressure.
 10. The process of claim 7 wherein said complex is decomposedby distillation at reduced pressure.
 11. The process of claim 7 whereinsaid complex is decomposed by cleaving the para-cresol isomer from saidcomplex with a lower aliphatic alcohol selected from the groupconsisting of ethanol, propanol, isopropanol and butanol.
 12. Theprocess of claim 7 wherein said complex is decomposed by hydrolysis withwater or alcohol to provide para-cresol isomer and said inorganic salt.13. The process of claim 12 wherein said inorganic salt recovered fordecomposition of the complex by hydrolysis is dehydrated and thenrecycled to complex with additional para-cresol isomer contained in amixture of methylated and ethylated phenolic compounds.
 14. The processof claim 7 wherein said anhydrous inorganic salt obtained fromdecomposing said complex is recycled to form a complex with additionalpara-cresol isomer contained in the mixture.
 15. The process of claim 7wherein para-cresol isomer obtained from decomposition of said complexis contained in a second mixture which includes minor amounts ofmeta-cresol isomer, said process further comprising the steps of:(a)adding one or more of said inorganic salts to said second mixture forforming a re-complexation product with the para-cresol isomer; (b)separating said re-complexation product from said second mixture; and(c) decomposing said re-complexation product to form para-cresol isomerand said inorganic salt.
 16. The process of claim 15, further comprisingsequentially treating mixtures containing successively higherconcentrations of para-cresol isomer and successively lowerconcentrations of meta-cresol isomer by process steps (a), (b) and (c).17. A process for separating para-cresol from a mixture containingpara-cresol, meta-cresol and minor amounts of ortho-ethyl phenol,xylenols, and ortho-cresol, said process comprising:(a) adding to saidmixture anhydrous or dehydrated calcium bromide in an amount to give amole ratio of calcium bromide to para-cresol in the mixture from about0.5 to one to about 1.5 to one in the presence of a non-aqueous solventto prodice a complex with the para-cresol, the mixture having atemperature in the range from about 20° C. to about 130° C. during theinorganic salt adding step; (b) separating said complex from saidmixture; and (c) decomposing said complex to yield predominantlypara-cresol and calcium bromide.
 18. The process of claim 17 whichincludes treating the mixture of methylated and ethylated phenoliccompounds resulting from the complexing and separating of thepara-cresol from the mixture to a separation process for removing anyone of the remaining methylated or ethylated phenolic compounds.